1. Technical Field
The present invention relates to an optical scanning device such as a laser printer or a digital copier and to an image forming apparatus that is disposed with this optical scanning device.
2. Related Art
An optical scanning device has been known that is disposed with a rotating polygon mirror that performs optical scanning by deflecting laser light emitted from a light source and an optical cover that covers this rotating polygon mirror. Specifically, in such a device, by disposing the optical cover that covers the entire rotating polygon mirror, dust and dirt are prevented from adhering to deflection surfaces of the rotating polygon mirror.
However, a plate member of the optical cover that covers an upper surface of the rotating polygon mirror is formed flatly.
Here, ordinarily, a first airflow that flows outward in a radial direction from a rotating shaft of the rotating polygon mirror is generated between the upper surface of the rotating polygon mirror and a ceiling plate when the rotating polygon mirror is rotated. Further, a second airflow that flows toward the ceiling plate along the deflection surfaces of the rotating polygon mirror is generated on the deflection surfaces of the rotating polygon mirror.
Thus, when the first airflow and the second airflow collide with each other in a case where the plate member that covers the upper surface of the rotating polygon mirror is formed flatly, there is nowhere for the air to escape upward, and the colliding air presses the rotating polygon mirror. In this manner, when the colliding air presses the rotating polygon mirror, irregularities occur in the rotation of the rotating polygon mirror.